The present invention relates to a positioning device and a positioning method.
A laser device is described, for example, in JP 2003-338795 A in which a laser beam emitted from a light projection section such as laser oscillators is aligned with and guided to a light receiving member such as optical fibers with use of optical members (movable members) such as lenses. In JP 2003-338795 A, the laser beam is positioned with respect to an optical fiber with a technique called wobbling in which the optical member is minutely vibrated with fixed amplitude and the change in intensity of the laser beam in the optical fiber is measured to detect the amount of center displacement of the laser beam so that the optical member is moved to the position where the received light intensity of the laser beam is maximized.
In the case of driving a movable member with a friction drive-type actuator, a difference may arise in the displacement amount of the movable member depending on driving directions. In that case, even when drive voltage is applied so that the movable member is moved forward and then backward so that it may return to the first position, the actual movable member moves to a position slightly displaced from the first position. This slight displacement leads to an error of wobbling, thereby causing such problems as the necessity of repeating a number of wobbling operations before accurate alignment is attained and the generation of offsets which cannot be eliminated depending gains of wobbling.
In such a laser device, a control method called hill climbing control is also known, the hill climbing control being composed of the steps for moving the optical member by a specified amount, checking whether or not the received light intensity increases, and moving the optical member continuously at a specified pitch in the direction of increasing the received light intensity until the increase in the received light intensity shifts to decrease. Although the hill climbing control enables more high precision alignment than the wobbling, it has a problem that positioning takes longer time than that in the wobbling.
The friction drive-type drive unit also has a problem in which repeated slide displacement in a minute area causes anomalous attrition in frictional contact sections, resulting in change of drive performance.